Organic/inorganic polymers prepared from polyisocyanates and polysilicic acids (hereinafter abbreviated: PP resins) have been known for about the last two decades. Their discovery and further development are first of all associated with the name of Dieter Dieterich as shown inter alia by the Hungarian patent specifications Nos. 168,586; 169,478; 176,469 and by chapter No. 2.4.9 regarding polyurethanes (by G. W. Becker and D. Braun) in the monograph "Kunststoff-Handbuch 7" (publisher: Editor K. Hansen, Munchen, 1983). Meanwhile industrial products based on these basic materials appeared on the market (e.g. the products "Wilkit" and "Wisitom" of the Willich Company, Germany) .
In comparison with the traditional molded polyurethane resins or foams, respectively, these inorganic/organic complymars possess a number of advantageous properties. Thus, e.g. their resistance to fire is significantly better (they are self-extinguishing), their solidity is less rapidly decreased at higher temperatures (&gt;100.degree. C.) and they are much cheaper. A disadvantage is that, products made of these materials and possessing good mechanical properties can be obtained only by rapidly accelerating the reaction with catalysts, which results in a gelation time of 2 to 3 minutes which is too rapid in many cases. However, the mechanical properties (bending strength, tensile strength and the like) of the traditional polyester resins cannot be achieved even in this case.
Bayer AG of Germany did pioneering work in the area of polysilicic acid/polyurethanes aimed at the utilization of MDI adducts sulfonated or made otherwise hydrophilic (German patent publications Nos. DE-AS 2,359,606; 2,359,612; foams: German patent publication No. DE-AS 2,450,834; concrete: Hungarian patent specification No. 168,586; preparation of sulfonated MDI adducts: German patent publications Nos. DE-OS 2,651,065 and 2,916,135). However, these modified polyisocyanates are substantially more expensive than the crude MDI [4,4-methylenedi(phenylisocyanate)] of technical grade.
According to our unpublished invention disclosed in the Hungarian patent application No. 2519/90, the features of PP resins can significantly be improved by adding aliphatic and/or cycloaliphatic and/or aromatic epoxy resins to the isocyanate component. However, this method also involves the drawback that the reaction proceeds too rapidly and the gelation occurs within 2 to 10 minutes. During this short period, inorganic and organic fillers, strengthening structural elements can be incorporated only to a limited extent. On the other hand, epoxy resins, particularly the less viscous aliphatic and cycloaliphatic epoxy resins, are very expensive: their price highly exceeds that of the crude MDI and other di- or polyisocyanates produced on an industrial scale.
In the Hungarian patent applications No. 2381/89 (published under No. T/54,182) and No. 2382/89 (published under No. T/54,183) the addition of so-called reactive diluents is suggested. These are built into the polymer during the hardening thereof; they are usually substantially cheaper than the isocyanate or epoxy component and, in addition, they improve the emulsifiability of the polyisocyanate in the water-glass. By using these ester-type reactive diluents, it is successfully possible to prepare products of high quality from crude MDI and thus, the preparation of expensive adducts sulfonated or made otherwise hydrophilic can be avoided. The process according to the Hungarian patent applications cited above, however, has the same drawback as those mentioned above: the time of gelation can be controlled only within a very short interval.